The long-term objective of this project is to understand the role of growth factors in proliferation of bladder urothelium. The effects of exogenous and autocrine bladder growth factors on cell growth in vitro can be tested under defined conditions using primary cultures of normal rodent bladder epithelium. Isolation of growth factors from normal rodent bladder will be facilitated by the use of heparin-affinity chromatography. The specific aims of this project are: (1) to determine if normal rodent bladder produces autocrine or paracrine growth factors, (2) to compare bladder-derived growth factors to known growth factors in terms of size, affinity for heparin, ability to stimulate 3T3 cell proliferation, angiogenic activity, transforming growth factor activity, binding to EGF and TGF-beta receptors, and recognition by specific anti-FGF and anti-PDGF antisera, (3) to examine the response of bladder urothelium in serum-free culture to exogenous growth factors, and (4) to examine the interplay between autocrine and exogenous growth factors in bladder epithelial cell proliferation. In the course of these experiments we will test several hypotheses regarding the nature of growth factor involvement in urothelial cell proliferation: (a) that growth of bladder urothelium is regulated by autocrine growth factor(s), (b) that exogenous growth factors are required for proliferation of bladder urothelium, and (c) that TGF-beta inhibits the growth of bladder epithelium.